Reliably conveying data and/or power along a drill string has become an increasingly important aspect of wellbore drilling operations. In particular, oil companies have become increasingly reliant on the use of real-time downhole information, particularly information related to the conditions associated with the drill bit, the bottom hole assembly (“BHA”), and the formation, to improve the efficiency of their drilling operations. Such real-time downhole information is often obtained via measurement while drilling (MWD) systems and/or logging while drilling systems (LWD), both of which utilize some form of downhole telemetry system to convey data between the downhole equipment and the surface equipment.
Numerous types of telemetry systems are commonly used in connection with MWD and LWD systems. For example, mud-pulse telemetry systems use modulated pressure or acoustic waves in the drilling fluid to convey data or information between the borehole equipment (e.g., a bottom hole assembly) and the surface equipment. However, mud-pulse telemetry systems have a relatively low data transmission rate of about 0.5-12 bits/second and, thus, substantially limit the amount of information that can be conveyed in real-time and, as a result, limit the ability of an oil company to optimize their drilling operations in real-time. Other telemetry systems such as electromagnetic telemetry (EM) via subsurface earth pathways and acoustic telemetry through drill pipe have been employed. These other telemetry systems also provide a relatively low data rate that may limit the ability of an oil company to employ sophisticated real-time data processing to optimize its drilling operations.
In contrast to telemetry systems that convey data via acoustic or electromagnetic waves (e.g., EM) through a fluid or the earth itself, wired drill pipe can convey data at a relatively high rate along the length of a drill string. Some wired drill pipe designs utilize conductive electrical connections between sections of drill pipe. However, these conductive electrical connections typically employ one or more moving parts such as springs and the like to ensure a high-quality electrical connection between drill pipe sections. Such moving parts can jam or become immovable and, thus, inoperative due to caked mud, cement, as well as other wellbore debris. Other wired drill pipe designs use inductive, magnetic, or current coupling between drill pipe sections.
One example of a wired drill pipe is disclosed in U.S. Pat. No. 3,696,332, issued to Dickson, Jr., et al., which discloses a drill pipe with insulated contact rings positioned in a shoulder at both ends of the pipe. The contact rings in a single segment of pipe are connected by a conductor wire that spans the length of the pipe. When a segment of drill pipe is made up with an adjoining segment of pipe, the contact ring in the first segment of pipe makes contact with a corresponding contact in the adjacent pipe section.
U.S. Pat. No. 6,717,501, issued to Hall, et al., discloses a system for transmitting data through multiple connected downhole components. Each component includes two communication elements and a conductor that connects the two. The communications elements are located in internal shoulders.
U.S. Pat. No. 6,929,493, issued to Hall, et al., discloses an electrical contact system with a first annular conductor embedded in an insulator in a housing in a tool joint that is adapted to mate with a second electrical contact in an end of an adjacent tool joint.